Same AS number from different location and Migration of IP addresses
Hello, Is that okay to use Same AS number for the two different site on different location? as well as any good documentation or link or deployment scenario where I can find the merging of two different AS into one AS? As well as what to do if I have an IP addresses as a service provider dependent block and want to migrate IP addressing to the IANA assigned ip addresses? how can i achieve that? regards Devang Patel
Hi Devang, a good start point is the Internet Routing Architecture book: http://www.ciscopress.com/bookstore/product.asp?isbn=157870233X Regards, Diogo On Fri, May 23, 2008 at 9:15 PM, devang patel <devangnp@gmail.com> wrote:
Hello,
Is that okay to use Same AS number for the two different site on different location? as well as any good documentation or link or deployment scenario where I can find the merging of two different AS into one AS? As well as what to do if I have an IP addresses as a service provider dependent block and want to migrate IP addressing to the IANA assigned ip addresses? how can i achieve that?
regards Devang Patel
-- ./diogo -montagner
(I'm sending from a non text-only system at the moment, sorry.) These should help on the merging part. [1]http://www.cisco.com/en/US/docs/ios/12_4/ip_route/configuration/guid e/hbgpdas.html [2]http://www.cisco.com/univercd/cc/td/doc/product/software/ios122s/122 snwft/release/122s25/fsbgpdas.htm [3]http://www.cisco.com/en/US/docs/ios/12_2t/12_2t11/feature/guide/ft11 bhla.html __________________________________________________________________ From: Diogo Montagner Sent: Sat 5/24/2008 8:25 AM To: [4]nanog@nanog.org Hi Devang, a good start point is the Internet Routing Architecture book: [5]http://www.ciscopress.com/bookstore/product.asp?isbn=157870233X Regards, Diogo On Fri, May 23, 2008 at 9:15 PM, devang patel <devangnp@gmail.com> wrote:
Hello,
Is that okay to use Same AS number for the two different site on different location? as well as any good documentation or link or deployment scenario where I can find the merging of two different AS into one AS? As well as what to do if I have an IP addresses as a service provider dependent block and want to migrate IP addressing to the IANA assigned ip addresses? how can i achieve that?
regards Devang Patel
-- ./diogo -montagner References 1. http://www.cisco.com/en/US/docs/ios/12_4/ip_route/configuration/guide/hbgpda... 2. http://www.cisco.com/univercd/cc/td/doc/product/software/ios122s/122snwft/re... 3. http://www.cisco.com/en/US/docs/ios/12_2t/12_2t11/feature/guide/ft11bhla.htm... 4. mailto:nanog@nanog.org 5. http://www.ciscopress.com/bookstore/product.asp?isbn=157870233X
On May 23, 2008, at 8:15 PM, devang patel wrote:
Hello,
Is that okay to use Same AS number for the two different site on different location?
To answer this specific question, Autonomous Systems should be topologically convex. This means, at the Internet interdomain routing (BGP) level, that packets cannot leave an AS in one place to get to locations in the same AS in some other place. So, to put two sites on one AS, there should be an internal connection between them, which can be done through your internal network, by a direct connection, or by a tunnel. Traffic might come to the AS at either site, and has to be routed internally to get to the other. See RFC 1930 and the material linked to in the other posts. Regards Marshall
as well as any good documentation or link or deployment scenario where I can find the merging of two different AS into one AS?
As well as what to do if I have an IP addresses as a service provider dependent block and want to migrate IP addressing to the IANA assigned ip addresses? how can i achieve that?
regards Devang Patel
On May 24, 2008, at 9:15 AM, Marshall Eubanks wrote:
On May 23, 2008, at 8:15 PM, devang patel wrote:
Is that okay to use Same AS number for the two different site on different location?
To answer this specific question, Autonomous Systems should be topologically convex. This means, at the Internet interdomain routing (BGP) level, that packets cannot leave an AS in one place to get to locations in the same AS in some other place.
So, to put two sites on one AS, there should be an internal connection between them, which can be done through your internal network, by a direct connection, or by a tunnel. Traffic might come to the AS at either site, and has to be routed internally to get to the other.
I am afraid I have to disagree with Marshall. The idea behind an AS when the routing protocols were written long ago may have been a contiguous domain, but there are lots of things the protocols did not originally envision. If you have two islands, and they each have a prefix which is globally routable, there is nothing wrong with the two islands sharing a single ASN. Island A announces Prefix A, and Island B announces Prefix B. Routing is done by prefix, not ASN, so there is no fear of Island A getting packets for Island B, and therefore no requirement for internal connectivity. And before anyone says anything about Island A not having connectivity to Island B, these are obviously not "transit free" networks, so each island can just point default. In fact, cisco even has a knob to listen to paths with your own ASN in it so you can do this without default (although I'm not sure I'd recommend that). It works fine and saves the community from burning an ASN. -- TTFN, patrick
Patrick, Your usage is quite consistent with the RFC 1930 guidelines on the use of AS, which probably does need some updating but does have an operational rather than a protocol theory viewpoint. Specifically, an AS is defined not as a business entity, not as a routing domain, but as: "...a connected group of one or more IP prefixes run by one or more network operators which has a SINGLE and CLEARLY DEFINED routing policy." In this case, the sites have a common, coordinated routing policy. I do agree that practicality does call for them to have a direct connection, but otherwise, they meet the requirement of being one or more IP prefixes run by one or more operators. I do hope they register their routing policy, with appropriate comments. Howard -----Original Message----- From: Patrick W. Gilmore [mailto:patrick@ianai.net] Sent: Saturday, May 24, 2008 11:11 AM To: NANOG list Subject: Re: Same AS number from different location and Migration of IPaddresses On May 24, 2008, at 9:15 AM, Marshall Eubanks wrote:
On May 23, 2008, at 8:15 PM, devang patel wrote:
Is that okay to use Same AS number for the two different site on different location?
To answer this specific question, Autonomous Systems should be topologically convex. This means, at the Internet interdomain routing (BGP) level, that packets cannot leave an AS in one place to get to locations in the same AS in some other place.
So, to put two sites on one AS, there should be an internal connection between them, which can be done through your internal network, by a direct connection, or by a tunnel. Traffic might come to the AS at either site, and has to be routed internally to get to the other.
I am afraid I have to disagree with Marshall. The idea behind an AS when the routing protocols were written long ago may have been a contiguous domain, but there are lots of things the protocols did not originally envision. If you have two islands, and they each have a prefix which is globally routable, there is nothing wrong with the two islands sharing a single ASN. Island A announces Prefix A, and Island B announces Prefix B. Routing is done by prefix, not ASN, so there is no fear of Island A getting packets for Island B, and therefore no requirement for internal connectivity. And before anyone says anything about Island A not having connectivity to Island B, these are obviously not "transit free" networks, so each island can just point default. In fact, cisco even has a knob to listen to paths with your own ASN in it so you can do this without default (although I'm not sure I'd recommend that). It works fine and saves the community from burning an ASN. -- TTFN, patrick
sure it is. the magical anycast, used by many for DNS service delivery oes exactly this. --bill On Fri, May 23, 2008 at 07:15:52PM -0500, devang patel wrote:
Hello,
Is that okay to use Same AS number for the two different site on different location?
regards Devang Patel
Hi, So if I will have the globally unique IP addresses for both the site which are located at different location then its perfectly fine to use the same as number in for same organisation having two different site located at different location...right!!! regards Devang Patel On Sat, May 24, 2008 at 10:40 PM, <bmanning@vacation.karoshi.com> wrote:
sure it is. the magical anycast, used by many for DNS service delivery oes exactly this.
--bill
On Fri, May 23, 2008 at 07:15:52PM -0500, devang patel wrote:
Hello,
Is that okay to use Same AS number for the two different site on different location?
regards Devang Patel
devang patel wrote:
So if I will have the globally unique IP addresses for both the site which are located at different location then its perfectly fine to use the same as number in for same organisation having two different site located at different location...right!!!
Right. But as others have stated you will have to do some configuration in order for the two locations to communicate *with each other*. There are a a few different ways to accomplish this as has been discussed previously. -- Jay Hennigan - CCIE #7880 - Network Engineering - jay@impulse.net Impulse Internet Service - http://www.impulse.net/ Your local telephone and internet company - 805 884-6323 - WB6RDV
Hi, Yes I do have link between two sites so I will configure routing accordingly so communication between two sites will follow that link... regards Devang Patel On Sun, May 25, 2008 at 10:25 PM, Jay Hennigan <jay@west.net> wrote:
devang patel wrote:
So if I will have the globally unique IP addresses for both the site which
are located at different location then its perfectly fine to use the same as number in for same organisation having two different site located at different location...right!!!
Right.
But as others have stated you will have to do some configuration in order for the two locations to communicate *with each other*.
There are a a few different ways to accomplish this as has been discussed previously.
-- Jay Hennigan - CCIE #7880 - Network Engineering - jay@impulse.net Impulse Internet Service - http://www.impulse.net/ Your local telephone and internet company - 805 884-6323 - WB6RDV
ascii art: (==== Internet =====) | | 192.0.2.10 192.0.2.10 | | AS-0 AS-0 | | 256.0.0.0 256.0.0.0 works a treat (as Joe Abley mentions as well). --bill On Sun, May 25, 2008 at 09:55:19PM -0500, devang patel wrote:
Hi,
So if I will have the globally unique IP addresses for both the site which are located at different location then its perfectly fine to use the same as number in for same organisation having two different site located at different location...right!!!
regards Devang Patel On Sat, May 24, 2008 at 10:40 PM, <bmanning@vacation.karoshi.com> wrote:
sure it is. the magical anycast, used by many for DNS service delivery oes exactly this.
--bill
On Fri, May 23, 2008 at 07:15:52PM -0500, devang patel wrote:
Hello,
Is that okay to use Same AS number for the two different site on different location?
regards Devang Patel
participants (8)
-
bmanning＠vacation.karoshi.com -
devang patel -
Diogo Montagner -
Howard C. Berkowitz -
Jay Hennigan -
Marshall Eubanks -
Patrick W. Gilmore -
Robert MacDonald